The 2-imidazolines and 1,4,5,6-tetrahydropyrimidines are known classes of compounds having many members and many utilities. Such compounds, or derivatives thereof, are commercially marketed as amphoteric surfactants, as corrosion inhibitors in the oil industry, and have even been examined as analgesics.
There are relatively few methods of preparing 2-imidazolines and 1,4,5,6-tetrahydropyrimidines described in the open literature. Those methods that are described range from a fairly crude "cooking" process of carboxylic acids and diamines to the process involving the reaction of nitriles with diamines. The latter process produces the imidazolines in high yields and high purity but is limited by the cost and availability of many nitriles. These and other methods of preparing imidazolines are described in a review article by R. J. Ferm and J. L. Riebsomer, Chemical Reviews, 54, 593-613 (1954).
Another method of preparing 2-imidazolines and 1,4,5,6-tetrahydropyrimidines comprises reacting a 2-oxazoline with a 1,2- or a 1,3-alkylenediamine. This method was reported by K. H. Magosch, Synthesis 1972, No. 1, 37 (1972). Crude yields varied from 60-61 percent for the imidazolines and varied from 19-73 percent for the tetrahydropyrimidines. The reactions were conducted by merely blending the reactants together and heating the mixture at a temperature of from about 180.degree. to 200.degree. C for periods of up to 10 hours.